Chronic Myeloid Leukaemia Developing During Long‐Term Alectinib Therapy Successfully Managed With Concomitant Nilotinib: A Case Report

ABSTRACT

Therapy‐related chronic myeloid leukaemia (t‐CML) is an extremely rare myeloid neoplasm. Here, we report a first case of CML developing during long‐term treatment with alectinib, a highly selective tyrosine kinase inhibitor (TKI) targeting anaplastic lymphoma kinase (ALK). A 53‐year‐old never‐smoking woman with ALK ‐positive non‐small cell lung cancer (NSCLC) developed mediastinal lymph node and brain metastases after curative surgery. Alectinib therapy achieved sustained systemic and intracranial disease control for nearly 3 years without serious adverse events. However, 3 years and 1 month after initiating alectinib, progressive leukocytosis with marked basophilia and circulating immature myeloid cells was observed. Bone marrow analysis confirmed the diagnosis of CML with BCR‐ABL1 fusion. Nilotinib was initiated while alectinib was continued, resulting in a rapid hematologic response without serious adverse events. Further accumulation of cases is needed to clarify the potential leukemogenic risk of ALK‐TKIs and to establish the safety and clinical utility of combined ALK‐TKI and BCR‐ABL‐TKI therapy.